


Into the Underverse

by Grieving_Angel



Series: Grieving's Undertale Stories [1]
Category: Undertale (Video Game)
Genre: F/F, I'm Bad At Tagging, M/M, Rating May Change
Language: English
Status: In-Progress
Published: 2019-06-14
Updated: 2019-06-18
Packaged: 2020-05-02 02:30:11
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings, Graphic Depictions Of Violence, Major Character Death
Chapters: 6
Words: 3,888
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19190113
Author URL: https://archiveofourown.org/users/Grieving_Angel/pseuds/Grieving_Angel
Summary: Sans has been kidnapped, and Frisk killed; now Undyne and Papyrus travel the multiverse with the Star Sanses trying to fix what has been broken.(Follows Papyrus and Undyne's adventures as well as Sans's)





	1. Accusations

It was a normal day, or at least it was supposed to be. 

Sans was walking home from Grillby's, like most tuesday nights. He was just passing the first window of his and his brother's house when things started to take a turn for the weird. 

"You little FUCKER, Naaaaaagggggg," came the bumptious cry of the Captain of the Royal Guard, Undyne. 

Spears sprang from the ground at Sans's feet. Caught off guard by the sudden barrage of spears Sans stumbled back.

 

-1hp

 

 

 

 

10/1 

 

Sans quickly stumbled to his feet, head on the swivel for his assaulter. Sans's eyes landed on an armor clad Undyne charging full speed ahead, heading straight toward him. Mind kicking into overdrive, Sans sidestepped the fish woman-shaped torpedo, leading Undyne to crash head first into the skeleton brothers' house, ripping a huge hole in the wall.

"UNDYNE, SO NICE OF YOU TO DROP IN! BUT, WHY DID YOU COME IN THROUGH THE WA…"

"NAAAAAAGGGGGG!!!" Undyne cut the bewildered Papyrus off, whirling around to turn a terrified Sans SOUL green.

This is when Sans really started to panic. He relied on his ability to dodge more than anything in battle, teleportation was out of the question (Undyne didn't know he could do that yet in this timeline, and he would like to keep it that way), and he didn't want to hurt her! Why was she attacking him out of the blue like this!? He hasn't done anything to piss her off… recently.

Undyne fired a barrage of spears towards the now panicking, small skeleton, neglecting to give him something to shield himself with. 

Right when he thought he would have to teleport, Frisk jumped in with their frying pan, desperately shielding their friend from… well, their friend. But they weren't able to block all of them and desperately took a blow.

-5  
15/20

-5  
5/1

"Get away from that murderer, punk!!" 

*You tell Undyne that you have no idea what she is talking about. Sans is your friend, and so is she, so they shouldn't fight.

"guys…" Sans timidly called, in shock from recent events.

"MY BROTHER IS NOT A MURDERER UNDYNE!" Papyrus bellowed appalled.

"Don't give me that bull crap, I know what I saw!" Undyne hollered. 

*You not-so calmly tell them both to stop shouting.

"Guys…" 

"Your brother murdered an innocent snowdrake right before my eyes!"

*You comment on how you don't think Sans's powers work like that, giving a shudder.

"MY BROTHER WOULD NEVER DO THAT… AND WHAT?!" 

"GUYS!" Sans yelled. Surprised and shocked that Sans -actually- yelled, the three turned to Sans, "may I say something?"

"Of COURSE, BROTHER!" Papyrus exclaimed, cutting off a grimacing Undyne from showing her distaste. 

*You readily agree with Papyrus.

"undyne, cut the carp," Sans turned to the angry fish woman, "and tell me what the shell you are talking about?"

"Don't play dumb with me!" Undyne accused, point a metaled claw towards the smallest of the brothers, "I saw what you did!"

"well, I obviously don't sea, what's going on, so you otter start talking."

"SANS, ENOUGH OF YOUR HORRIBLE PUNS!"

"sor-sea," 

*You kindly point out to Sans that his puns aren't "calming the tide"

"NOT YOU, TOO!" 

"Naaaaaagggggg!" Undyne screamed as she slammed a spear into the ground sending snow and slush flying through the air, "look here I want answers!" 

"so do i," Sans calmly retorted, bringing up his CHECK box to show Undyne.

 

SANS THE SKELETON

HP 5/1

AT 1

DF 1

LV 0

THE WEAKEST ENEMY… IS VERY CONFUSED.

….

"Alright, so it wasn't you," Undyne admitted begrudgingly, "but that means that you have a doppelganger running around killing people." 

*You ask Undyne if she noticed anything off about the other Sans.

"YES! DID YOU NOTICE ANYTHING DIFFERENT ABOUT THIS OTHER SANS YOU SPEAK OF?" 

"Now that you mention it, yeah," Undyne said, taking off her helmet. "He had his hood up." 

"is that it?" Sans prodded, earning an eye roll from Undyne.

"No… uh, let me think," Undyne scrunched her brow, "he might have been taller, and … um…"

*You apologize for interrupting, but you are wondering why Undyne didn't attack "Sans" when, who ever they are, killed the snowdrake.

"Oh, yeah, he teleported," Undyne stated matter of factly, "can you do that Sans?"

"yes, i can," Sans sighed, so much for keeping it a secret. 

"Oh, I just remembered," Everyone turned to Undyne, "I left the stove on in my new house!" Everyone groaned. "Oh yeah, and his eyes were glowing purple, red, and cyan."

Sans could feel a cold sweat started on the back of his neck. "and that wasn't alarming why?"

*You ask if they were just going to ignore the fact that Undyne's new house was probably burning down at the moment.

"Well, I know skeletons have this thing where you can make your eyes get all glowie when you use magic, so I thought it was normal," Undyne shrugged.

"two things wrong with that. one, I only have one eye; two, my eye is cyan and yellow."

*Apparently we are ignoring the fact that Undyne's house is probably burning down right now. 

"UNDYNE, CAN YOU TAKE US TO WHERE YOU SAW THIS OTHER SANS?" 

"Sure thing, nerds!" Undyne turned around and heading in the direction she came.

"excuse me, i don't want to jump the shark, but i'm still a little GREEN around the gills,"

"Oh, right," 

~~~

A single eye watched as the group moved away, dark mass swirling around the form.

"They are heading in your direction. Make sure to have the traps ready, Dust," Nightmare thought towards his 'friend'.


	2. Ashes to Ashes and Dust to Dust

**Summary for the Chapter:**

> Meet Dust

Undyne and Papyrus sprinted through the Snowdin forest, with Frisk and Sans piggy backing, so they wouldn't have to worry about keeping up.

*You ask Undyne what she was doing so deep in Snowdin forest in the first place.

"I, uh, was getting the weekly report from the K9 unit,"

"DON'T THEY GO TO YOUR HOUSE TO DELIVER IT EVERY SATURDAY?"

"Shut up, Nerd!"

"undyne, it's winds-day," sans commented, hood flapping in the wind.

"I said 'SHUT UP'! And it's Tuesday, NERD!" 

*You tell Undyne that she isn't helping her case.

"Nag, FINE… Alphys upgraded my armor to withstand extreme temperatures. SO NOW I CAN CHASE NERDS LIKE YOU ALL OVER THE UNDERGROUND! NAAAAAAGGGGGG!" 

"WHY WAS THAT SO HARD TO EXPLAIN?" 

*You say that it's because Undyne is in love.

"SHUT UP YOU NERD!" 

"that still doesn't explain what you were doing out this far," 

"Oh, yeah, I was testing it out and kinda…" Undyne came to a sudden stop, leading to Papyrus take a few steps in front of her.

"KINDA WHAT?" Papyrus asked turning to her.

Undyne set down Frisk, summoning a spear, eyes never leaving something behind Papyrus. "We're here, and we have company,"

Papyrus spun to face whatever was behind him.

There they were, a near identical copy of Sans, about a head taller. They were wearing a blue hoodie, grey hood up, front unzipped to reveal what the figure was wearing underneath, just a simple gray sweater, black sweatpants, and sneakers. They had a bright red scarf wrapped around their neck, fluttering in a barely existing breeze. But, the skeleton's most prominent feature was their face: half lidded eyelids framed one red eye light and one red and purple, their mouth did not smile; matter of fact, their face betrayed no emotion at all. They looked at the four intruders as if they were just uninteresting, borderline annoying, like a small child holding up a small, dull trinket to someone who truly doesn't care.

They stood in the middle of a large snow field, several yards in length. Hardly any snow falling to obscure their view. They were hovering, about six feet in the air, as if standing on something invisible.

They were covered in dust.

"Heya," the strange monster said in a chilling monotone voice, "name's Dust."

"Naaaaaagggggg! I don't care who you are, now who are you?!" Undyne asserted, jabbing her spear in the non-skeleton brother's direction.

Dust cocked his head to one side, "I told you, I'm Dust."

"You better start making sense or you're gonna be!"

"WHAT MY FRIEND MEANS TO SAY IS: WHAT ARE YOU DOING?"

"Yeah! And who sent you,"

*You add your curiosity on what this strange monster was after.

"and why are you hurting people?"

*You also politely ask if they could please not fight. 

The other skeleton stared at them. Unmoving, completely still except for the fluttering of his scarf in the wind. 

Then, he laughed.

He threw back his head and howled. The wind echoed with the insane laugh of a mad man. The very sound of it freezing the already frozen air. 

"Do you really think I would be that easy," Dust screamed at them an insane smile on his face. 

Something unseen swept Frisk, Undyne, and Papyrus of their feet, causing Papyrus to drop Sans.

"Let me answer your questions," Dust cheered, a bit to enthusiastically.

Sans teleported behind Dust preparing to attack him, only to get knocked out of the air and flung across the field.

"No, this fight cannot be avoided,"

Sans got up, but his eyes were drawn downward to right beneath where Dust was hovering.

"I was sent by Nightmare,"

The snow beneath Dust was disturbed, as if something massive was there. 

Dust summoned several sharp, red bones.

"I hurt people to get stronger,"

Sans reached out with his magic and sure enough, there was someone.

Dust aimed the projectiles at Frisk, Papyrus, and Undyne.

"I am after the origin- Aagghh!"

Sans grabbed the SOUL of the creature Dust was standing on, proceeding to flig it across the field and crashing into a grove of pine trees. Turning the trees into toothpicks, and sending Dust careening to the ground.

Undyne took this opportunity to turn Dust's SOUL green, preparing an attack of her own.

"Let go of me you Bitch!" Dust cried, recalling his bone, one piercing through Undyne's shoulder.

-500

1000/1500

Undyne lost her grip on Dust's SOUL, allowing him to spring up and run too the destroyed trees.

"Brother!" Dust called as snow and debris shifted as some massive form slithered out of the trees.

"I suppose introductions are in order," Dust beamed, evilly.

"This is my brother, Ashes." 

A towering naga skeleton flickered into existence behind Dust.

The Skele snake was at least eighteen feet long and had six arms. It's mouth boar wicked fangs and eyes glowed a bloody red, but the most disturbing thing was how much it looked like Papyrus. 

"Sure, Nightmare might have turned him into a nightmare demon during the resurrection process," Dust cheerfully commented, "but at least we are together again. That's all that matters."

*You waveringly squeak your confusion.

"Of course," Dust madly beamed at the child, "I killed him." 

The four souls in the clearing freeze from shock.

It was Dust's turn.

Red bones exploded from the ground, impaling everyone except Frisk and Sans, who barely got out of the way.

-250

430/680

-500

500/1500

*You give Undyne and Papyrus some dog salad. 

"THANK YOU, TINY HUMAN FRIEND," 

*Papyrus's hp was fully restored, Undyne wants to refuse the salad.

"undyne, one more hit from that guy and your dead," 

*You offer her instant noodles instead, she accepts. Her hp is now, 590/1500.

"You better be ready, because I'm not letting you get another hit one me!" Undyne challenged, charging forward.

"NYAHAHA! THAT'S THE SPIRIT UNDYNE!" Papyrus called, quickly following Undyne in her charge.

Before they could reach Dust however, Ashes sent them flying into the trees with a single swipe of it's tall. 

"You want to go, PUNK!?" Undyne called too the demon skeleton.

"DON'T WORRY ABOUT US, BROTHER AND TINY HUMAN! WE WILL TAKE CARE OF THE SNAKE SKELETON, JUST CONCENTRATE ON APPREHENDING THE SANS LOOK ALIKE CALLED DUST!" Papyrus called to Frisk and Sans before joining Undyne in battle.

~story split~

~Frisk and Sans~

"Kill them!" Dust commanded his brother before firing another barrage of bones towards the two remaining in the field. 

Frisk and Sans nimbly dodged out of the way now that they were not distracted.

"you ready, kid?" 

*You tell Sans that you were born ready, equipping the temy armor.

Frisk ran forward, equipping the empty gun and throwing it at Dust with a battle cry. 

Dust easily sidestepped the offending weapon. Then proceeded to give Frisk an 'are you serious' look.

"- Nuuaaggh!" 

Frisk had created the perfect distraction, in the moments that Dust was focused on Frisk, Sans had teleported behind Dust and summoned a bone filled with KR. That bone attack was now protruding from Dust's chest.

Dust screamed in pain inflicted from KARMA, collapsing to the ground do to the shear agonie.

"stay down," Sans advised, pulling up a CHECK on the other.

 

DUSTTALE SANS  
AKA DUST

HP 2546/3384

AT 1425

DF 696

LV 58

IS AFTER YOU

 

"what the…"

Dust grabbed Sans by his SOUL and threw him to the middle of the field, to where Dust and Ashes were before. Sans hurried to his feet, preparing another attack. A loud crackling could be heard through the air as power surged around Sans.

Power that was not Sans's own.

Sans cried out in surprise and pain as his magic flow was cut off causing him to collapse again.

*You call out to Sans, trying to run over to him… only to get cut off by a wall of spiked bones.

Sans slowly opened his eyes, head ringing. Looking down, threw the disterbed snow, Sans saw the surface they were fighting on.

"oh, shit!" Sans exclaimed.

They were on a frozen lake.

Sans looked up to where Dust and Frisk were currently duking it out. 

"guys, we have to stop fighting!" He cried out to them. 

Frisk turned to him to see what was going on. Only to watch as several bones sprung up around Sans, caging him in.

Sans's face contorted to a fearful look, as the bones shattered the ice sending Sans plunging into the icy cold depths of the frozen lake.

~story split~

~Frisk~

Frisk watched in horror as their friend vanished under the ice.

"Shit," Dust exclaimed, rushing over to the growing cracks in the ice, he stripped of his hoodie and threw it to the side where the wind caught it blowing it to shore where it was entangled in the branches of the trees.

Frisk watched as Dust dove in after Sans. Guilt rushing through them as the ran to shore out of fear of falling in.

The enemy was willing to risk their life for Sans, but Frisk couldn't out of pure cowardice. 

*You call for help, tears streaming down your face.


	3. Heard

**Summary for the Chapter:**

> Short chapter  
> Sorry

~Papyrus and Undyne~

Papyrus weaved his way through a grove of tightly packed trees in an attempt to get Ashes off his tail.

With a loud roar, Ashes began to rip the trees out of the ground by the roots.

"Well, fuck," Undyne flatly stated giving away her location in the trees. 

Ashes world around, locking eyes with Undyne, who was perched on a branch far above the current reach of the demon.

Ashes reared up, like a snake ready to strike, reaching for Undyne.

"Double, fuck!" Undyne cried, leaping away from the reaching hands, losing her grasp on the tree and falling.

Papyrus reached out with his blue magic, catching Undyne mid fall.

"Thanks, Nerd!" 

Despite the fact that Undyne and Papyrus have dueled each other many times, they just couldn't patch each other's weak spots when attacking. Because of this, they were put on the complete defensive.

"Naaaaaagggggg! This is so stupid!" Undyne complained as her and Papyrus ducked behind a thick trunked tree.

"SHH," Papyrus hushed.

" Oh, shush my ass," Undyne whined, "it's not like that thing already know where we are! It must have some sort of super hearing… or smell… or sight,"

"NO, I MEAN, UGH, DID YOU HEAR THAT?"

"Hear what?" Undyne said, straining her ears to try and make out what Papyrus was talking about. There it was…

Undyne and Papyrus looked at each other: it was Frisk calling for help.


	4. Frozen tears

Papyrus and Undyne burst into the field, only to find a large lake with cracked ice floating on the surface. Dust was nowhere to be seen, the only evidence that he had ever been there at all was his dusty hoodie caught in the branches of a tree a few yards to the left of where the two stood, yet there was no evidence of Sans either.

The two quickly spotted Frisk, around three yards to the right of where they emerged from the forest, on there knees, crying.

"TINY HUMAN, WHAT IS THE MATTER? ARE YOU OK? WHAT HAPPENED TO MY BROTHER?" Papyrus jogged over, embracing his friend.

"What happened, Punk?" Undyne asked softly, despite the teasing nickname.

*You explain how the Dust person did something to Sans's magic, after they got a decent hit on him. You say that Sans tried to warn them that they were on thin ice… 'pun not intended' you say when Papyrus grimaced. Anyway, Sans fell in and Dust dove after him.

"What, didn't he want us dead…. nevermind! I'm going after them!" Undyne announced turning to the lake.

~Ashes~

The DUSTTALE Papyrus sighed. 

He was painfully stuck between two thick trees and he couldn't rip them from their roots or wiggle out from in-between them, nor could he un-summon his body to become a floating head with out his brother.

He was stuck.

~Sans~

It was so cold.

The adrenaline from the fight had worn off and Sans's limbs where starting to grow numb. Bubbles escaped from his mouth as he started to lose consciousness.


	5. Frozen Bones

~Undyne~

Undyne knew that the water was cold, it was frozen for a reason, but she would risk life and limb for the ones she cared for.

She might not have ever shown her fondness of Sans (literally never), but she has learned to care for the smallest of her senteries none the less. 

A price that came with constantly hanging out with his younger brother.

What she wasn't expecting was for her armor to actually heat up the water around her: it wasn't to the point that it was comfortable, but it was a lot more manageable than sub zero temperatures. 

Making a mental note to remember to thank Alphys for thinking of her more aquatic nature, Undyne dove into the dark waters. (Thankfully the dark wasn't too much of a problem either, generations living underground will do that.)

As she continued swimming downward she saw… Sans, swimming downward… no that wasn't Sans! That was Dust!

Undyne summoned a teal spear, hurling it past Dust's head. 

A warning shot.

The spear illuminated the waters surrounding it on it's decent.

But the spear did its purpose.

Dust turned to the armor clad Undyne surprise cracking through his apathy plastered face, only to quickly be replaced with annoyance.

Undyne smirked, now it was just a waiting game. She could breathe underwater, he could not. Even if he was a skeleton (skeletons can slightly absorb air from water through their outer bone layers; however, it is not as nearly as good as gills) he would have to go up for air eventually!... But then again, the longer she took to find Sans, the more dangerous it became for him.

Dust immediately summoned two dragonode skulls, taking Undyne by surprise. Not that she hasn't seen things like them before (Papyrus loved showing his off), she didn't expect it to be a common thing. They way both Sans and Papyrus talked about them sure made them seem like they weren't.

However, firing the… Blasters, Undyne thought that was what they were called… only seemed to heat up the water to boiling point. Luckily, Undyne let her armor carry her out of the Blasters' range. 

Using this as an advantage, Undyne swam under Dust before the bubbles cleared enough to let him see that he had missed his target.

Using her GREEN magic to pin dust in place, she fired an onslaught of spears up at the skeleton; however, only a few hit before he summoned another skull to shield himself.

 

2492/3384

The blaster charged and fired.

However, do to the fact that the Blaster was obscuring his view of his target and didn't see she swam out of range again. 

When the Blaster fired, it turned some water into steam. This steam formed bubbles. Bubbles that rose up, surrounding Dust.

Dust screamed in frustration as he was effectively blinded for a solid minute with bubbles from his own attack.

Undyne mentally patted herself on the back for the quick thinking, as she resumed her search for Sans. Adrenaline rushing through her gills from the near possibility of being cooked alive. 

Summoning a plethora of spears, she sent them gently spiraling through the water to illuminate the way forward. 

There he was! 

Bubbles rose from his mouth as he slowly sunk into the swirling darkness. 

Undyne screamed as she felt water rush past her as she was forcefully dragged away from her friend. Frustrated dread filling her as she watched as Dust swam past her heading toward the unconscious Sans. 

But Dust made no move to hurt Sans, instead he scooped the smaller skeleton bridal style. Letting go of Undyne's SOUL, Dust used his blue magic to carry himself and unknowing victim up towards the surface. 

After not even a moment's hesitation, Undyne followed.


	6. Cracks

~Dust~

 

Dust emerged not to far from where his hoodie was. Heaving and coughing, he marched his way to the shore. 

 

Giving his prisoner a once over… by the stars, he wasn't even shivering, didn't even look like he was breathing. 

 

That wasn't good.

 

"WHAT DID YOU DO TO UNDYNE?!" 

 

The frantic question caused Dust to jerk his head toward the source of the voice, only to internally cringe as it just caused the water in his head to slosh. 

 

"NNNNAAAAAAAAAAAAAAAAAAAAAAGGGGGGG!!!" Undyne let out a fearsome battle cry and flailed her arms while brandishing duel spears. While Dust could appreciate (not) that it was an attempt to make her look more intimidating, it just made her look like a child at a waterpark.

 

He waved his hand to cast the magical command that would unsummon pa- Ashes'- body and grabbing his coat in the same motion.

 

Sidestepping an onslaught of spears, he ported. 

 

~

 

'I have apprehended the target.'

 

'Good, everyone else, status report.'

 

'There is only four of us Nightmare, you don't need to be so formal.'

 

'*Growl*"

 

'Ok, fine. The source code destination devices have been placed in each of the golden flower fields.'

 

'I found and exterminated the weed.'

 

'Never, going to use the proper  "formalities", no matter how much Nightmare threatens you, are ya Horror?'

 

'Nope, also can't find the kid' 

 

'I wonder why' 

 

'You run into them, Dust?'

 

'Yes, but lucky for us the kid seems to be terrified of water, otherwise this mission of ours would have been a bust.' 

 

'heh'

 

'You knew.'

 

'Whatever do you mean?'

 

'You KNEW that me and Ashes were going to go up against all of  _ them _ didn't you!? Why didn't you warn is!?' 

 

'Ashes and I.'

 

'Nevermind, just meet me at the rendezvous point.' 


End file.
